Short carbon fiber reinforced thermoplastic composite material and preparation method and use thereof

Abstract

The present invention provides a short carbon fiber reinforced thermoplastic composite material, and its preparation method and use. The composite material includes short carbon fibers and a thermoplastic resin; the thermoplastic resin includes polyphenylene sulfide and polyethersulfone; wherein the content of the short carbon fibers is 10% to 40% by mass of the total mass of the composite material, and the mass ratio of the polyphenylene sulfide to the polyethersulfone is 1:0.3 to 1:3. The present invention obtains a composite material with high thermal conductivity, high thermal stability and excellent mechanical properties by using a certain amount of polyethersulfone and polyphenylene sulfide and incorporating short carbon fibers. The composite material is also particularly suitable for forming a final product by 3D printing.

Description

Technical Field

[0001] The present invention relates to a short carbon fiber reinforced thermoplastic composite material, a preparation method and use thereof, and belongs to the field of composite materials. In addition, the composite material of the present invention is particularly suitable for 3D printing to prepare a final product. Background Art

[0002] The polytetrafluoroethylene (PTFE)-based pipes currently used in seawater cooling systems and boiler heat exchange systems have poor strength, low thermal conductivity, and poor rigidity at high temperatures, which affects their long-term use and increases subsequent maintenance costs.

[0003] Carbon fiber-reinforced thermoplastic composites (CFRPs) offer advantages such as high strength, high corrosion resistance, easy processing, and recyclability. They are expected to be used in extreme applications such as boilers, nuclear power plants, and thermal power plants, especially in highly corrosive seawater cooling systems. CFRPs offer a viable alternative to traditional metal / PTFE liners for cooling systems, but their high-temperature mechanical properties and thermal conductivity remain to be studied.

[0004] Reference 1 provides a carbon fiber-reinforced thermoplastic resin composite material with high mechanical strength and a method for manufacturing the same. This method uses laser irradiation on carbon fibers at a dose of 0.01-200 mgy. The carbon fibers are typically heated and laminated with the thermoplastic resin before or after irradiation. Compared to composites manufactured without laser irradiation, the resulting composite material exhibits improved tensile strength, flexural strength, and impact resistance.

[0005] Reference 2 provides a carbon fiber reinforced thermoplastic composite material and its preparation method. In this method, carbon fibers are placed in a helium space for plasma modification treatment, thereby etching the carbon fiber surface to increase the tensile strength of the carbon fibers. Nano-silica and silane coupling agents are added to the carbon fibers. The silane coupling agent strengthens the bonding between the carbon fibers and the nano-silica, thereby increasing the impact resistance of the carbon fibers. Graphene and peracetic acid are added to the carbon fibers to increase the chemical activity and surface free energy of the carbon fibers, thereby increasing the wettability with the thermoplastic resin, improving the interfacial bonding performance of the composite material, and greatly increasing the hardness of the carbon fiber thermoplastic composite material.

[0006] Reference 3 provides a modified carbon fiber reinforced thermoplastic resin composite material. This material, by first modifying the carbon fibers with a hyperbranched polymer and then mixing them with a thermoplastic resin, can achieve a more uniform distribution of the carbon fibers within the composite material, significantly improving the mechanical properties of the composite material.

[0007] Reference 4 provides a carbon fiber-reinforced MC nylon thermoplastic composite and its preparation method. This method uses caprolactam monomer as the resin matrix and employs in-situ anionic polymerization to prepare a thermoplastic polymer on carbon fiber materials via a vacuum infusion (VARI) process. This method addresses existing problems such as uneven distribution of thermoplastic resin within the carbon fiber, complex preparation processes, and long production cycles, while also improving the mechanical properties of the composite.

[0008] It can be seen that although the existing technology has conducted certain research on carbon fiber reinforced thermoplastic composites, there is less research on high-temperature performance, and there is room for further exploration.

[0009] References:

[0010] Reference 1: CN108638601A

[0011] Reference 2: CN116554637A

[0012] Reference 3: CN111548600A

[0013] Reference 4: CN108203506A Summary of the Invention

[0014] Problems to be solved by the invention

[0015] As mentioned above, the current research on carbon fiber reinforced thermoplastic composites mainly focuses on the mechanical properties, impact resistance, wear resistance and other aspects of thermoplastic composites, while there is less research on the high-temperature performance of carbon fiber reinforced thermoplastic composites. When used in extreme situations such as boilers, nuclear power plants, and exhaust gas heat exchanger pipes in thermal power plants, higher requirements are placed on the high-temperature performance of composite materials. Therefore, the high-temperature performance of carbon fiber reinforced thermoplastic composites has research value.

[0016] Based on the above situation, the present invention provides a short carbon fiber reinforced thermoplastic composite material, which mixes polyethersulfone resin and polyphenylene sulfide resin in the form of powder, and introduces short carbon fibers into polyphenylene sulfide and polyethersulfone, thereby obtaining a composite material with high thermal conductivity, high thermal stability and excellent mechanical properties. The composite material is also particularly suitable for forming a final product by 3D printing.

[0017] In addition, the present invention also provides a method for preparing the short carbon fiber reinforced thermoplastic composite material.

[0018] Furthermore, the present invention also provides a use of a short carbon fiber reinforced thermoplastic composite material in a cooling system or a heat exchange pipe.

[0019] Solutions for solving problems

[0020] The present invention first provides a short carbon fiber reinforced thermoplastic composite material, wherein the composite material comprises short carbon fibers and a thermoplastic resin;

[0021] The thermoplastic resin includes polyphenylene sulfide and polyethersulfone;

[0022] The content of the short carbon fibers is 10% to 40% by mass of the total mass of the composite material, and the mass ratio of the polyphenylene sulfide to polyether sulfone is 1:0.3 to 1:3.

[0023] According to the composite material of the present invention, the thermoplastic resin is used in the form of a powder raw material.

[0024] According to the composite material of the present invention, the length of the short carbon fibers is 100-250 μm.

[0025] According to the composite material of the present invention, the composite material satisfies at least one of the following conditions:

[0026] i) the composite material has a flexural strength of 40 MPa or more;

[0027] ii) the Young's modulus of the composite material is greater than 6 GPa;

[0028] iii) The thermal conductivity of the composite material is greater than 0.6 W / mK.

[0029] Secondly, the present invention also provides a method for preparing the composite material according to the present invention, which comprises the following steps:

[0030] Thermoplastic resin preparation steps: mixing polyphenylene sulfide and polyethersulfone powders to obtain a thermoplastic resin matrix;

[0031] The step of blending: blending the thermoplastic resin matrix with short carbon fibers to obtain a mixture;

[0032] Hot pressing step: pouring the mixture into a mold, applying pressure, and heating to maintain the temperature and pressure;

[0033] Cooling and demoulding steps: After cooling to room temperature, demoulding is performed to obtain a composite material.

[0034] According to the preparation method of the present invention, the step of preparing the thermoplastic resin further includes a ball milling step, the rotation speed of the ball mill is 300-500 rpm, and the ball milling time is 3-5 hours.

[0035] According to the preparation method of the present invention, in the blending step, the blending time is 5 to 20 minutes.

[0036] According to the preparation method of the present invention, in the hot pressing step, the pressurizing comprises: applying a pressure P1, then releasing the pressure, and reapplying a pressure P2, wherein P1 is 10-20 MPa and P2 is 1-3 MPa;

[0037] The heating rate is 5-15°C / min;

[0038] During the heat-insulating and pressure-maintaining reaction, the temperature is 250-290° C., the pressure is 1-3 MPa, and the reaction time is 10-30 min.

[0039] According to the preparation method of the present invention, in the step of cooling and demoulding, the cooling rate is 4-7°C / min.

[0040] In addition, the present invention also provides a use of the composite material according to the present invention or the short carbon fiber reinforced thermoplastic composite material prepared by the preparation method according to the present invention in a cooling system or a heat exchange pipe.

[0041] Effects of the Invention

[0042] The composite material of the present invention, by combining certain polyethersulfones with polyphenylene sulfide and incorporating short carbon fibers, not only achieves excellent heat resistance and thermal conductivity, but also enhances rigidity while maintaining good flexural resistance (retaining good toughness). Specifically, using polyphenylene sulfide as one of the base resins ensures excellent heat resistance, while the introduction of polyethersulfone alleviates the problem of poor compatibility between short carbon fibers and polyphenylene sulfide, which can lead to peeling and failure. The overall result is a composite material that not only exhibits excellent heat resistance, but also enhances rigidity, thermal conductivity, and thermal stability through the use of short carbon fibers. Furthermore, the use of polyethersulfone improves toughness, resulting in improved workability.

[0043] The short carbon fiber reinforced thermoplastic composite material provided by the present invention not only improves the mechanical properties of the composite material, but also improves the thermal conductivity and thermal stability of the composite material, thereby improving the heat dissipation performance of the composite material. It is expected to be applied to extreme situations such as exhaust gas heat exchanger pipelines in boilers, nuclear power plants, and thermal power plants.

[0044] In addition, the composite material of the present invention is also suitable for forming a product of a final desired shape through 3D printing. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 The results of the flexural test of the composite materials obtained in Comparative Example 1, Example 1, Example 2 and Example 3 are shown;

[0046] Figure 2The results of the flexural test of the composite materials obtained in Comparative Example 1, Comparative Example 2, Reference Example and Example 3 are shown;

[0047] Figure 3 The results of the flexural test of the composite materials obtained in Comparative Example 1, Comparative Example 3, and Comparative Example 4 are shown;

[0048] Figure 4 The graph shows the results of dynamic mechanical testing (DMA) of the composite materials obtained in Comparative Example 1, Example 1, Example 2 and Example 3;

[0049] Figure 5 The results of thermal conductivity tests on the composite materials obtained in Comparative Example 1, Example 1, Example 2 and Example 3 are shown;

[0050] Figure 6 The results of thermogravimetric analysis tests on the composite materials obtained in Comparative Example 1, Example 1, Example 2 and Example 3 are shown. DETAILED DESCRIPTION

[0051] The following is a detailed description of the present invention. The following description of the technical features is based on representative embodiments and specific examples of the present invention, but the present invention is not limited to these embodiments and specific examples. It should be noted that:

[0052] In this specification, a numerical range expressed using "a numerical value A to a numerical value B" means a range including the endpoints A and B.

[0053] In this specification, the numerical range expressed using "above" or "below" means a numerical range including the number.

[0054] In this specification, the use of "may" includes both the meaning of performing a certain process and the meaning of not performing a certain process.

[0055] In this specification, the use of "optional" or "optional" indicates that certain substances, components, execution steps, application conditions and other factors are used or not used.

[0056] In this specification, "normal temperature" or "room temperature" refers to an indoor ambient temperature of "23±2°C".

[0057] In this specification, the unit names used are all international standard unit names, and unless otherwise stated, the "%" used indicates weight or mass percentage.

[0058] In this specification, the use of “substantially” means that the standard deviation from a theoretical model or theoretical data is within a numerical range of 5%, preferably 3%, and more preferably 1%.

[0059] When the terms “include” and / or “comprising” are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or their combinations.

[0060] References throughout this specification to "some specific / preferred embodiments," "other specific / preferred embodiments," "embodiments," etc., mean that the particular elements (e.g., features, structures, properties, and / or characteristics) described in connection with the embodiments are included in at least one embodiment described herein and may or may not be present in other embodiments. Furthermore, it should be understood that the elements may be combined in any suitable manner in various embodiments.

[0061] The present invention mainly provides a short carbon fiber reinforced thermoplastic composite material and a preparation method thereof. The present invention is based on the following insights:

[0062] It has been found that the current research on carbon fiber reinforced thermoplastic composites in the prior art mainly focuses on the study of mechanical properties, and there is less research on high-temperature performance. However, the use of composite materials in cooling systems or boiler heat exchange systems has high requirements for high-temperature performance. Therefore, the high-temperature performance of carbon fiber reinforced thermoplastic composites has research significance. Through research, the inventors found that by using polyethersulfone and polyphenylene sulfide as a matrix, polyethersulfone can improve the molding effect of polyphenylene sulfide while serving as a thermoplastic matrix material. Compared with the use of a single polyphenylene sulfide as a matrix, polyphenylene sulfide / polyethersulfone has higher machinability and is suitable for multiple processes such as hot pressing and injection molding. At the same time, further introducing short carbon fibers into the above-mentioned matrix material can further improve the mechanical properties and thermal conductivity of the composite material, thereby being expected to be applied in extreme cases such as exhaust gas heat exchanger pipes in boilers, nuclear power plants, and thermal power plants.

[0063] (First aspect)

[0064] A first aspect of the present invention provides a short carbon fiber reinforced thermoplastic composite material, comprising short carbon fibers and a thermoplastic resin.

[0065] Thermoplastic resin

[0066] Considering applications in cooling systems or boiler heat exchange systems, the present invention primarily uses polyphenylene sulfide (PPS) as the matrix thermoplastic resin. The inventors have also discovered that using PPS alone as the matrix results in loose powder after molding, resulting in poor molding results. Therefore, for processing and molding purposes, polyethersulfone (PES) is further added as a coagulant to assist in the molding of PPS. This improves the toughness of the matrix material, making it more workable and suitable for multiple processes such as hot pressing and injection molding.

[0067] In some specific embodiments, the thermoplastic resin is used in the form of a powdered raw material.

[0068] In some specific embodiments, the mass ratio of polyphenylene sulfide to polyethersulfone is 1:0.3 to 1:3, for example, 1:0.5, 1:1, 1:1.5, 1:2, 1:2.5, etc. When the mass ratio of polyphenylene sulfide to polyethersulfone is 1:0.3 to 1:3, the resin matrix itself has excellent flexural strength and modulus.

[0069] In addition, the thermoplastic resin may further comprise other thermoplastic resins commonly used in the art, provided that the technical effects of the present invention are achieved. Preferably, the content of the other thermoplastic resin is less than 10% by mass, more preferably less than 5% by mass, of the total mass of the thermoplastic resin.

[0070] Short carbon fiber

[0071] In the present invention, the carbon fibers used mainly include short carbon fibers. By introducing short carbon fibers into the thermoplastic resin, not only the mechanical properties of the composite material can be improved, but also the thermal conductivity and thermal stability can be improved at the same time.

[0072] From the perspective of further improving the mechanical properties and lightweighting of the molded products, the short carbon fibers used in the present invention can be PAN-based, asphalt-based, rayon-based, and other commonly used short carbon fibers in this field. From the perspective of the balance between the strength and elastic modulus of the obtained molded products, asphalt-based short carbon fibers are more preferred.

[0073] In some specific embodiments, the length of the short carbon fibers is 100-250 μm, for example, 120 μm, 150 μm, 180 μm, 200 μm, 220 μm, etc.

[0074] In addition, without hindering the technical effects of the present invention, the carbon fibers may also include other carbon fibers commonly used in the art, such as long carbon fibers and continuous carbon fibers. Preferably, the content of the other carbon fibers is less than 10% by mass of the content of the short carbon fibers, more preferably less than 5% by mass.

[0075] Composition of composite materials

[0076] In the composite material of the present invention, from the perspective of improving the mechanical properties and high-temperature properties of the composite material, its composition is as follows: the content of the short carbon fiber is 10% to 40% by mass of the total mass of the composite material, for example, it can be 12% by mass, 15% by mass, 19% by mass, 25% by mass, 28% by mass, 30% by mass, 32% by mass, 35% by mass, 38% by mass, etc.; based on the total mass of the thermoplastic resin and the short carbon fiber as 100% by mass, the content of the polyethersulfone is 25% to 75% by mass of the total mass of the thermoplastic resin and the short carbon fiber, for example, it can be 30% by mass, 35% by mass, 40% by mass, 45% by mass, 50% by mass, 55% by mass, 60% by mass, 65% by mass, or 70% by mass.

[0077] Properties of composite materials

[0078] The composite material of the present invention satisfies at least one of the following performance characteristics:

[0079] i) the composite material has a flexural strength of 40 MPa or more, preferably 45 MPa or more;

[0080] ii) the Young's modulus of the composite material is greater than 6 GPa, preferably greater than 6.5 GPa;

[0081] iii) The thermal conductivity of the composite material is 0.4 W / mK or higher, preferably 0.6 W / mK or higher, more preferably 1.0 W / mK or higher, and further preferably 1.3 W / mK or higher.

[0082] (Second aspect)

[0083] A second aspect of the present invention provides a method for preparing the short carbon fiber reinforced thermoplastic composite material according to the first aspect, comprising the following steps:

[0084] Thermoplastic resin preparation steps: mixing polyphenylene sulfide and polyethersulfone powders to obtain a thermoplastic resin matrix;

[0085] The step of blending: blending the thermoplastic resin matrix with short carbon fibers to obtain a mixture;

[0086] Hot pressing step: pouring the mixture into a mold, applying pressure, and heating to maintain the temperature and pressure;

[0087] Cooling and demoulding steps: After cooling to room temperature, demoulding is performed to obtain a composite material.

[0088] Thermoplastic resin formulation

[0089] The step of preparing the thermoplastic resin of the present invention mainly involves mixing polyphenylene sulfide and polyethersulfone powders as thermoplastic resin raw materials to obtain a thermoplastic resin matrix.

[0090] In the mixing step, in order to improve the uniformity of resin distribution, a ball milling method can be used. There is no particular limitation on the ball milling method, and a method commonly used in the art can be used, such as ball milling for 3 to 5 hours, with 1.5 to 2.5 hours of forward and reverse rotation respectively, and the ball milling speed is 300 to 500 rpm.

[0091] Blending

[0092] The blending step in the present invention is to mix the short carbon fibers with the thermoplastic resin matrix to obtain a mixture.

[0093] In the blending step, in order to improve the uniformity of the mixture, stirring can be performed by ball milling or other methods during the blending process, and the stirring time is 5 to 20 minutes.

[0094] Hot Pressing

[0095] The hot pressing step in the present invention is a step of heating the mixed material in a mold by pressurizing and then performing a heat and pressure-maintaining reaction.

[0096] In some specific embodiments, the pressurizing includes: applying pressure P1, then releasing the pressure, and re-applying pressure P2, wherein P1 is 10~20 MPa, for example, 12 MPa, 15 MPa, 18 MPa, etc.; P2 is 1~3 MPa, for example, 1.5 MPa, 2 MPa, 2.5 MPa, etc., and the air is ensured to be discharged from the mold by pressurizing to 10~20 MPa, releasing the pressure, and re-pressurizing to 1~3 MPa.

[0097] In some specific embodiments, the heating rate is 5-15°C / min. If the rate is too high, the heat transfer will be uneven, affecting the resin fluidity and curing effect. For example, it can be 8°C / min, 10°C / min, 12°C / min, 14°C / min, etc.

[0098] In some specific embodiments, during the heat preservation and pressure maintenance reaction, the temperature is 250~290°C, for example, it can be 255°C, 260°C, 265°C, 270°C, 275°C, 280°C, 285°C, etc. When the temperature is higher than 290°C, the material is easily oxidized, and when the temperature is lower than 250°C, the material is not completely melted; the pressure is 1~3MPa, for example, it can be 1.5MPa, 2MPa, 2.5MPa, etc.; the reaction time is 10~30min, for example, it can be 15min, 20min, 25min, etc.

[0099] In some specific embodiments, before the hot pressing step, the steps of laying a release cloth and closing the film can also be included, specifically including laying a release cloth on the lower surface of the hot pressing mold, pouring the mixture into the mold and closing the mold after laying the top layer of release cloth. By laying the release cloth, it can be ensured that the sample can be easily demolded after heating and cooling.

[0100] Cooling and demoulding

[0101] In the present invention, the step of cooling and demoulding is a step of slowly cooling the hot-pressed composite material to room temperature and finally demoulding the composite material to obtain the composite material.

[0102] In some specific embodiments, the cooling method includes cooling by a water cooling system, and controlling the temperature control rate to be 4~7℃ / min, for example, 4.5℃ / min, 5℃ / min, 5.5℃ / min, 6℃ / min, 6℃ / min, etc.

[0103] Additional Steps

[0104] The composite material obtained after demoulding may be subjected to a post-processing step to obtain a composite material that can be used. The post-processing may include surface treatment, processing, and the like.

[0105] In some preferred embodiments, the preparation method may include the following steps:

[0106] S1. Preparation of thermoplastic matrix: Select polyphenylene sulfide and polyethersulfone powders in a fixed weight ratio and mix them by ball milling for 4 hours (400 rpm, two hours each for forward and reverse directions) to ensure uniform dispersion;

[0107] S2. Short carbon fiber blending: Add the short carbon fiber to step S1 and continue mixing and stirring for 10 minutes;

[0108] S3. Laying release cloth: Lay release cloth on the lower surface of the hot pressing mold to ensure that the sample is easy to demold after heating and cooling;

[0109] S4, mold closing: Pour the mixture of S1 and S2 evenly into the mold, and close the mold after laying the top layer of release cloth;

[0110] S5. Pressure: Apply 10-20 MPa of pressure, then release it and reapply 1-3 MPa of pressure to ensure that air can be discharged from the mold;

[0111] S6, hot pressing process: the heating rate is controlled at 10°C / min, the temperature is raised to 250°C-290°C and the pressure is kept at this temperature for 20 minutes;

[0112] S7, cooling: slowly cooling by water cooling system, with the cooling rate controlled at 4-7°C / min to room temperature;

[0113] S8, demoulding: slowly remove the sample using a special demoulding device and remove the demoulding cloth on the upper and lower surfaces;

[0114] S9, surface treatment: polish the sample surface to ensure normal processing;

[0115] S10, test sample processing: The sample is processed by CNC to obtain a specimen suitable for flexural resistance, thermal conductivity, and dynamic mechanical testing;

[0116] S11. Surface post-treatment: Grind and polish the sample to obtain a uniform sample surface.

[0117] (Third aspect)

[0118] A third aspect of the present invention provides use of the short carbon fiber reinforced thermoplastic composite material obtained according to the preparation method described in the first aspect or the second aspect in a cooling system or a heat exchange pipe.

[0119] In some other specific embodiments, such products can be realized by using the composite material of the present invention and ultimately by 3D printing.

[0120] Example

[0121] The embodiments of the present invention will be described in detail below with reference to the examples, but it will be understood by those skilled in the art that the following examples are merely illustrative of the present invention and should not be construed as limiting the scope of the invention. Where specific conditions are not specified in the examples, the methods were performed according to conventional conditions or the conditions recommended by the manufacturer. Where the manufacturers of the reagents or instruments are not specified, they are all conventional products that can be obtained commercially.

[0122] Comparative Example 1

[0123] (1) Preparation of thermoplastic resin matrix: PPS / PES powder with a certain mass ratio (PPS:PES = 1:1) was poured into a ball mill and placed in a ball mill (dry mixing). The ball mill speed was set to 400 rpm and the ball milling time was 4 h to obtain PPS / PES mixed resin powder.

[0124] (2) Hot pressing: Pour the PPS / PES mixed resin powder into the mold, use a hydraulic press to apply a pressure of 20 MPa to compact the powder, release the pressure and apply pressure again and maintain a pressure of about 2 MPa, raise the temperature from 25°C to 260°C with the hydraulic press, maintain for 20 minutes, cool from 260°C to 50°C with the hydraulic press, and release the pressure.

[0125] (3) Cooling and demolding: Air cooling to 25°C and demolding to obtain the thermoplastic composite material.

[0126] (4) Processing and post-processing: The sample is processed by CNC to obtain the specimen, and the specimen is polished to obtain a uniform sample surface.

[0127] Example 1

[0128] (1) Preparation of thermoplastic resin matrix: PPS / PES powder with a certain mass ratio (PPS:PES = 1:1) was poured into a ball mill and placed in a ball mill (dry mixing). The ball mill speed was set to 400 rpm and the ball milling time was 4 h to obtain PPS / PES mixed resin powder.

[0129] (2) Short carbon fiber mixing: Add the short carbon fiber to the PPS / PES mixed resin powder at a mass ratio of 10% of the total mass of the composite material and dry-mix for 10 minutes to obtain a mixture.

[0130] (3) Hot pressing: Pour the mixture into the mold, use a hydraulic press to apply a pressure of 20 MPa to compact the powder, release the pressure and apply pressure again and maintain a pressure of about 2 MPa, heat the hydraulic press from 25 ° C to 260 ° C, maintain for 20 minutes, cool the hydraulic press from 260 ° C to 50 ° C, and release the pressure.

[0131] (4) Cooling and demolding: Air cooling to 25 °C, demolding to obtain short carbon fiber reinforced thermoplastic composite materials.

[0132] (5) Processing and post-processing: The sample is processed by CNC to obtain the specimen, and the specimen is polished to obtain a uniform sample surface.

[0133] Example 2

[0134] (1) Preparation of thermoplastic resin matrix: PPS / PES powder with a certain mass ratio (PPS:PES = 1:1) was poured into a ball mill and placed in a ball mill (dry mixing). The ball mill speed was set to 400 rpm and the ball milling time was 4 h to obtain PPS / PES mixed resin powder.

[0135] (2) Short carbon fiber mixing: Add short carbon fiber to PPS / PES mixed resin powder at a mass ratio of 20% of the total mass of the composite material and dry-mix for 10 minutes to obtain a mixture.

[0136] (3) Hot pressing: Pour the mixture into the mold, use a hydraulic press to apply a pressure of 20 MPa to compact the powder, release the pressure and apply pressure again and maintain a pressure of about 2 MPa, heat the hydraulic press from 25 ° C to 260 ° C, maintain for 20 minutes, cool the hydraulic press from 260 ° C to 50 ° C, and release the pressure.

[0137] (4) Cooling and demolding: Air cooling to 25 °C, demolding to obtain short carbon fiber reinforced thermoplastic composite materials.

[0138] (5) Processing and post-processing: The sample is processed by CNC to obtain the specimen, and the specimen is polished to obtain a uniform sample surface.

[0139] Example 3

[0140] (1) Preparation of thermoplastic resin matrix: PPS / PES powder with a certain mass ratio (PPS:PES = 1:1) was poured into a ball mill and placed in a ball mill (dry mixing). The ball mill speed was set to 400 rpm and the ball milling time was 4 h to obtain PPS / PES mixed resin powder.

[0141] (2) Short carbon fiber mixing: Add short carbon fiber in an amount of 30% of the total mass of the composite material into the PPS / PES mixed resin powder and dry-mix for 10 minutes to obtain a mixture.

[0142] (3) Hot pressing: Pour the mixture into the mold, use a hydraulic press to apply a pressure of 20 MPa to compact the powder, release the pressure and apply pressure again and maintain a pressure of about 2 MPa, heat the hydraulic press from 25 ° C to 260 ° C, maintain for 20 minutes, cool the hydraulic press from 260 ° C to 50 ° C, and release the pressure.

[0143] (4) Cooling and demolding: Air cooling to 25 °C, demolding to obtain short carbon fiber reinforced thermoplastic composite materials.

[0144] (5) Processing and post-processing: The sample is processed by CNC to obtain the specimen, and the specimen is polished to obtain a uniform sample surface.

[0145] Comparative Example 2

[0146] (1) Preparation of thermoplastic resin matrix: PPS / PES powder with a certain mass ratio (PPS:PES = 1:1) was poured into a ball mill and placed in a ball mill (dry mixing). The ball mill speed was set to 400 rpm and the ball milling time was 4 h to obtain PPS / PES mixed resin powder.

[0147] (2) Hot pressing: Pour the PPS / PES mixed resin powder into the mold, use a hydraulic press to apply a pressure of 20 MPa to compact the powder, release the pressure and apply pressure again and maintain a pressure of about 2 MPa, raise the temperature from 25°C to 290°C with the hydraulic press, maintain for 20 minutes, cool from 290°C to 50°C with the hydraulic press, and release the pressure.

[0148] (3) Cooling and demolding: Air cooling to 25°C and demolding to obtain the thermoplastic composite material.

[0149] (4) Processing and post-processing: The sample is processed by CNC to obtain the specimen, and the specimen is polished to obtain a uniform sample surface.

[0150] Comparative Example 3

[0151] (1) Preparation of thermoplastic resin matrix: PPS / PES powder with a certain mass ratio (PPS:PES = 0.75:0.25) was poured into a ball mill and placed in a ball mill (dry mixing). The ball mill speed was set to 400 rpm and the ball milling time was 4 h to obtain PPS / PES mixed resin powder.

[0152] (2) Hot pressing: Pour the PPS / PES mixed resin powder into the mold, use a hydraulic press to apply a pressure of 20 MPa to compact the powder, release the pressure and apply pressure again and maintain a pressure of about 2 MPa, raise the temperature from 25°C to 260°C with the hydraulic press, maintain for 20 minutes, cool from 260°C to 50°C with the hydraulic press, and release the pressure.

[0153] (3) Cooling and demolding: Air cooling to 25°C and demolding to obtain the thermoplastic composite material.

[0154] (4) Processing and post-processing: The sample is processed by CNC to obtain the specimen, and the specimen is polished to obtain a uniform sample surface.

[0155] Comparative Example 4

[0156] (1) Preparation of thermoplastic resin matrix: PPS / PES powder with a certain mass ratio (PPS:PES = 0.25:0.75) was poured into a ball mill and placed in a ball mill (dry mixing). The ball mill speed was set to 400 rpm and the ball milling time was 4 h to obtain PPS / PES mixed resin powder.

[0157] (2) Hot pressing: Pour the PPS / PES mixed resin powder into the mold, use a hydraulic press to apply a pressure of 20 MPa to compact the powder, release the pressure and apply pressure again and maintain a pressure of about 2 MPa, raise the temperature from 25°C to 260°C with the hydraulic press, maintain for 20 minutes, cool from 260°C to 50°C with the hydraulic press, and release the pressure.

[0158] (3) Cooling and demolding: Air cooling to 25°C and demolding to obtain the thermoplastic composite material.

[0159] (4) Processing and post-processing: The sample is processed by CNC to obtain the specimen, and the specimen is polished to obtain a uniform sample surface.

[0160] Reference Example

[0161] (1) Preparation of thermoplastic resin matrix: PPS / PES powder with a certain mass ratio (PPS:PES = 1:1) was poured into a ball mill and placed in a ball mill (dry mixing). The ball mill speed was set to 400 rpm and the ball milling time was 4 h to obtain PPS / PES mixed resin powder.

[0162] (2) Short carbon fiber mixing: Add short carbon fiber in an amount of 30% of the total mass of the composite material into the PPS / PES mixed resin powder and dry-mix for 10 minutes to obtain a mixture.

[0163] (3) Hot pressing: Pour the mixture into the mold, use a hydraulic press to apply a pressure of 20 MPa to compact the powder, release the pressure and apply pressure again and maintain a pressure of about 2 MPa, heat the hydraulic press from 25 ° C to 290 ° C, maintain for 20 minutes, cool the hydraulic press from 290 ° C to 50 ° C, and release the pressure.

[0164] (4) Cooling and demolding: Air cooling to 25 °C, demolding to obtain short carbon fiber reinforced thermoplastic composite materials.

[0165] (5) Processing and post-processing: The sample is processed by CNC to obtain the specimen, and the specimen is polished to obtain a uniform sample surface.

[0166] Performance Testing

[0167] 1. Flexural strength test: The composite materials obtained in Comparative Example 1 and Examples 1 to 3 were tested for flexural strength and stiffness. The specific test method is as follows: a three-point bending test was performed using a universal testing machine (Tinius Olsen 50ST) with a loading rate of 2 mm / min and the test standard was GB / T 1449-2005. The support span was set to 32 mm (16 times the sample thickness). The results are shown in Figure 2. Figure 1 shown.

[0168] The composite materials obtained in Comparative Example 1 and Comparative Example 2, Reference Example and Example 3 were tested for flexural strength and stiffness. The results are as follows: Figure 2 shown.

[0169] The composite materials obtained in Comparative Example 1, Comparative Example 3, and Comparative Example 4 were tested for flexural strength and stiffness. The results are as follows: Figure 3 shown.

[0170] Depend on Figure 1 It can be seen that the composite materials obtained in Examples 1 to 3 (samples with short carbon fiber contents of 10%, 20% and 30%) have little effect on the flexural strength while having a significant improvement effect on the stiffness compared to Comparative Example 1 (sample with a short carbon fiber content of 0%). That is, the examples improve the stiffness without causing a loss of toughness.

[0171] Depend on Figure 2It can be seen that Comparative Example 2 and the reference example (samples with short carbon fiber contents of 0% and 30% respectively prepared at 290°C) have lower flexural strength and stiffness than Comparative Example 1 and Example 3 (samples with short carbon fiber contents of 0% and 30% respectively prepared at 260°C), but the reference example shows that the reduction in mechanical properties can actually be suppressed at excessively high processing temperatures.

[0172] Depend on Figure 3 It can be seen that Comparative Example 3 (PPS:PES=0.75:0.25) has lower flexural strength and modulus than Comparative Example 1 (PPS:PES=1:1), and the molding effect of the surface sample is poor; Comparative Example 4 (PPS:PES=0.25:0.75) has higher flexural strength than Comparative Example 1 (PPS:PES=1:1), but its modulus is greatly reduced (easier to bend). Overall, Comparative Example 1 is a more ideal matrix ratio.

[0173] 2. Dynamic Mechanical Test: Dynamic mechanical tests were performed on the composite materials obtained in Comparative Example 1 and Examples 1 to 3. The specific test method was as follows: DMA 8000 (PerkinElmer) was used for three-point bending dynamic mechanical analysis. The sample size was 50 mm × 7 mm × 2 mm. The temperature scan range was from room temperature to 350°C. The scan was performed in air at a heating rate of 3°C / min and a frequency of 1 Hz. The initial strain was set to 0.01 mm. The results are shown in Figure 2. Figure 4 shown.

[0174] Depend on Figure 4 It can be seen that the composite materials of Examples 1 to 3 have a higher storage modulus and a lower Tan δ peak value than the composite material of Comparative Example 1, indicating that the composite materials of Examples 1 to 3 improve the stiffness of the matrix resin and the ability to resist interfacial (organic / inorganic interface) shear slip, making the high modulus composite material less prone to deformation and improving the material's ability to resist matrix deformation.

[0175] 3. Thermal conductivity test: The thermal conductivity of the composite materials obtained in Comparative Example 1 and Examples 1 to 3 was tested using a laser thermal conductivity meter (LFA467, Netzsch, Selb; Germany). The test temperature was 25°C, and the thermal conductivity was calculated using the following formula:

[0176] λ=C p ×D×ρ

[0177] Where λ is the thermal conductivity, W / (m·K); C P is the specific heat capacity, J / (kg·K); D is the thermal diffusion coefficient, mm 2 / s; ρ is the density of the material, kg / m 3 The results are as follows Figure 5 shown.

[0178] Depend on Figure 5 It can be seen that the thermal conductivity of the composite materials obtained in Examples 1 to 3 is significantly improved compared to the composite material of Comparative Example 1, wherein the thermal conductivity of Example 1 is increased by 116% relative to that of Comparative Example 1, the thermal conductivity of Example 2 is increased by 335% relative to that of Comparative Example 1, and the thermal conductivity of Example 3 is increased by 388% relative to that of Comparative Example 1.

[0179] 4. Thermal analysis test: The composite materials obtained in Comparative Example 1 and Examples 1 to 3 were subjected to thermal analysis test. The specific test method is as follows: The thermal stability test was conducted using thermogravimetric analysis (TGA, PerkinElmer STA8000) in accordance with GB / T 13464 "Thermal Analysis Test Method for Thermal Stability of Materials". The samples were heated in synthetic air at 20°C / min. -1 The rate of heating is from 30℃ to 900℃. Figure 6 shown.

[0180] Depend on Figure 6 It can be seen that the temperature and value of the exothermic peak of the sample increase with the increase of the short carbon fiber content. The change in the pyrolysis temperature of Examples 1 to 3 and Comparative Example 1 shows that the short carbon fibers effectively improve the thermal stability of the composite material.

[0181] It should be noted that, although the technical solutions of the present invention are described with specific examples, those skilled in the art will appreciate that the present invention should not be limited thereto.

[0182] While various embodiments of the present invention have been described above, the above descriptions are intended to be illustrative, non-exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is selected to best explain the principles of the embodiments, their practical applications, or technological improvements in the marketplace, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A short carbon fiber reinforced thermoplastic composite material, characterized in that: The composite material includes short carbon fibers and thermoplastic resin; The thermoplastic resin includes polyphenylene sulfide and polyethersulfone; The content of the short carbon fibers is 10% to 35% by mass of the total mass of the composite material, and the mass ratio of the polyphenylene sulfide to the polyether sulfone is 1:

1. The length of the short carbon fibers is 100-250 μm; The composite material satisfies at least one of the following conditions: i) the composite material has a flexural strength of 40 MPa or more; ii) the Young's modulus of the composite material is greater than 6 GPa; iii) The thermal conductivity of the composite material is greater than 0.4 W / mK.

2. The composite material according to claim 1, characterized in that The thermoplastic resin is used in the form of a powdery raw material.

3. A method for preparing a composite material according to claim 1 or 2, characterized in that: The following steps are involved: Thermoplastic resin preparation steps: mixing polyphenylene sulfide and polyethersulfone powders to obtain a thermoplastic resin matrix; The step of blending: blending the thermoplastic resin matrix with short carbon fibers to obtain a mixture; Hot pressing step: pouring the mixture into a mold, applying pressure, and heating to maintain the temperature and pressure; Cooling and demoulding steps: After cooling to room temperature, demoulding is performed to obtain a composite material.

4. The preparation method according to claim 3, characterized in that The step of preparing the thermoplastic resin further includes a ball milling step, wherein the rotation speed of the ball mill is 300-500 rpm and the time of the ball milling is 3-5 hours.

5. The preparation method according to claim 3 or 4, characterized in that In the blending step, the blending time is 5 to 20 minutes.

6. The preparation method according to claim 3 or 4, characterized in that In the hot pressing step, the pressurization includes: applying a pressure P1, releasing the pressure, and reapplying a pressure P2, wherein P1 is 10-20 MPa and P2 is 1-3 MPa; The heating rate is 5-15°C / min; During the heat-insulating and pressure-maintaining reaction, the temperature is 250-290° C., the pressure is 1-3 MPa, and the reaction time is 10-30 min.

7. The preparation method according to claim 3 or 4, characterized in that In the step of cooling and demoulding, the cooling rate is 4-7°C / min.

8. Use of the composite material according to claim 1 or 2 or the short carbon fiber reinforced thermoplastic composite material prepared according to the preparation method according to any one of claims 3 to 7 in a cooling system or a heat exchange pipe.

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